Water Quality Analysis: Determining Biochemical Oxygen Demand (BOD)

This report details an experiment to determine the Biochemical Oxygen Demand (BOD) of a water sample, a critical parameter for assessing water quality. The experiment aims to quantify the amount of dissolved oxygen consumed by microorganisms during the decomposition of organic matter. The procedure involves treating water samples with specific reagents, refluxing, and titrating to measure oxygen demand. The results indicate the concentration of microorganisms in the water, which is used to infer the level of pollution. High BOD levels suggest a significant presence of organic waste and microbial activity, confirming the water is polluted. The report also includes references to relevant studies and methodologies for BOD determination, emphasizing its importance in environmental monitoring and wastewater treatment.

Running Head: BIOCHEMICAL OXYGEN DEMAND (BOD)
Biochemical oxygen demand (BOD)
Name
Institution

BIOCHEMICAL OXYGEN DEMAND (BOD) 2
Abstract
The primary objective of this experiment determines the BOD of a water sample. In this case,
BOD is a critical water quality parameter to quantify. BOD indicates the measure of broke down
oxygen devoured by microorganisms amid the deterioration of natural issue for example and is
determined as the underlying DO focus short the last DO fixation over a given timeframe. Water
samples with high Bod can be referred to as polluted.

BIOCHEMICAL OXYGEN DEMAND (BOD) 3
Objective
To determine BOD in a sample of water.
Theory
Biochemical oxygen demand (BOD) is characterized as the measure of oxygen required by
microscopic organisms while balancing out decomposable organic matter under high-impact
conditions (John, 2013). The BOD test is broadly used to decide the pollution quality of
household and industrial wastewaters; it indicates the amount of oxygen used to break down
waste. BOD test is unique among other ways of determining water quality, Water with high
BOD shows that there is high levels of microorganism activities (Kwok, 2005).
BOD is a critical water quality parameter to quantify. It speaks to the measure of broke
down oxygen devoured by microorganisms amid the deterioration of natural issue in an example
and is determined as the underlying DO focus short the last DO fixation over a given timeframe.
Most generally (Mullis, 2013), the multi-day BOD (BOD5) is what is estimated; the explanation
behind this is the BOD test was first used in England, the theory behind this is no rivers in
England they take more than 5 days for water to flow from source to the lake or ocean .
High BOD level means there is a great deal of organic matter present in the example and
is normal in wastewater (Qiao, Hu & Li, 2016). The BOD of sewage must be estimated all
through the treatment procedure to guarantee that the water body it is being released into will
keep up worthy DO levels and the environment can endure. Ordinary BOD5 values are 110-400
mg/L for raw wastewater, 5-15 mg/L for gushing, and 0 for an unpolluted stream (Cross &
Summerfelt, 2007).
Apparatus

BIOCHEMICAL OXYGEN DEMAND (BOD) 4
 Reflux apparatus
 Erlenmeyer flask
 Hot plate with sufficient powder for ¼ w/cm3 heating surface
Reagents
 Standard potassium dichromate solution, 0.0417 M: Dissolve 12.259 g
K2Cr2°'7 standard primary grade, previously dried at 103 •c for two h, in
distilled water and dilute to 1000 ml.
 Sulphuric acid reagent: Add AgSO, r reagent or technical grade, crystals or
powder, to cone.H2so. At the rate of 5.5 g Ag2SOJkg H2so•.Let it stand for
1to 2 days to dissolve Ag2SO•.
 Ferron indicator solution: Dissolve 1.485 g 1,1O·phenanthroline monohydrate,
and 695 mg FeS0•.7H20 in distilled water and dilute to 1 00 ml.
 Standard ferrous ammonium sulfate (FAS) titrant, approximately 0.25 M: Dissolve 98 g
Fe (NH) 2 (S0)26H20 in distiled water. Add 20 ml cone. H2SO4cool, and dilute
to 1000 m
 Mercuric sulphate, HgSO,
 Sulphamic
 Potassium hydrogen phthalate (KHP) standard:
Procedure
a) Samples Treatment with COD of > 50 mg 02/l
10.0 ml of the sample was put in a 250-ml refluxing cup. Include 0.2 g HgS04, a few
glass beads, and very gradually include 5.0 m sulphuric acid reagent with blending to

BIOCHEMICAL OXYGEN DEMAND (BOD) 5
disintegrate HgS04. Chill while mixing to stay away from conceivable loss of unpredictable
materials (John, 2013). Include 5.0 ml0.250 N K2Cr207 arrangement and blend. Connect the
carafe to the condenser and turn on cooling water. Include the staying sulphuric acid reagent (10
m) through the open end of the condenser. Keep whirling and blending white including the
sulphuric acid reagent
CAUTION: the flux mixture was mixed thoroughly before the heat was applied this was to
prevent local heating of the bottom of the flask,
The open end of the condenser was secured with a stopper to keep outside material from
entering refluxing, blend and reflux for 2 hr. The condenser was chilled and washed off. The
reflux condenser was detached, and the mix weakened to about twice its volume with30 ml of
distilled water. Cool to room temperature and titrate the abundance K2Cr201with FAS, utilizing
0.1O to 0.15 m (2 to 3 drops) ferritin Indicator. Although the amount of ferrous marker isn't
necessary, use a similar volume for all titrations. The end of the titration process should be noted,
to form a pink color .the blue green color may return similarly, reflux and titrate a clear
containing the reagents and a volume of distilled water equivalent to that of the example
(Hassapis, 1991).
b) Procedure for low-COD samples
The methodology of 4 a) was pursued with two individual cases: (I) utilize standard
0.00417 M K2Cr201, and (ii) titrate with 0.025 M FAS. Exercise extraordinary consideration
with this technique because even a hint of the fundamental issue on the dish sets or from the
climate may cause net mistakes (Abdalla & Hammam,2014). If a further increment In
affectability Is required, concentrate a more significant volume of test before processing under

BIOCHEMICAL OXYGEN DEMAND (BOD) 6
reflux as pursues. Every one of the reagents was added to an example bigger than 50 ml and
decreased the absolute amount to 150 m by boiling in the refluxing flask open to the environment
without the condenser appended, (Daudpoto, Talpur, Shah & Khooharo, 2018). A measure of
HgSO.was registered to be included (before fixation) based on a load proportion of 10:1,
Hgso.c1·using the measure of c1·present in the first volume of the test. Bring a clear reagent
through a similar system (Jouanneau et al,. 2014). This procedure has the upside of concentrating
the example without critical misfortunes of effectively processed unstable materials. Difficult to-
process unstable elements, for example, unpredictable acids are lost. However, improvement is
increased over customary evaporative focus strategies ,
Results and calculations
item Volume ,ml
final 13.3
black initial 0
volume used 6.9
KHP final 19.2
initial 12.3
volume used 6.9
sample final 25.6
initial 19.3
volume used 6.4
Concentration Abundance
1 0.021
2 0.056
3 0.118
4 0.183
5 0.259

BIOCHEMICAL OXYGEN DEMAND (BOD) 7
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
0
0.05
0.1
0.15
0.2
0.25
0.3
Concentration
Abadancee
Discussion and conclusion
From the data obtained it shows clearly from the concentration (BOD) that the water has
high microorganisms hence can be termed as polluted water, Biological Oxygen Demand (BOD)
is a proportion of the oxygen utilized by microorganisms to disintegrate this waste. BOD test is a
method for deciding the rate of take-up of disintegrated oxygen by the rate of natural living
beings in a body of water goes through oxygen. It is anything but an exact quantitative test, even
though it is broadly utilized as an indicator of the quality of water. On the off chance that there
is an extensive amount of natural waste in the water supply, there will likewise be a lot of
microbes present attempting to break down this waste. For this situation, the demand for oxygen
will be high (because of the considerable number of microscopic organisms), so the BOD level
will be high.

BIOCHEMICAL OXYGEN DEMAND (BOD) 8
References
Abdalla, K. Z., & Hammam, G. (2014). Correlation between biochemical oxygen demand and chemical
oxygen demand for various wastewater treatment plants in Egypt to obtain the biodegradability
indices. International Journal of Sciences: Basic and Applied Research, 13(1), 42-48.
Daudpoto, M., Talpur, M., Shah, F., & Khooharo, A. (2018). Response Surface Methodology for
removal of Biological Oxygen Demand (BOD) through RBC. SINDH UNIVERSITY
RESEARCH JOURNAL -SCIENCE SERIES, 50(04), 591-594. doi:
10.26692/sujo/2018.12.0095
John, G. (2013). American national standard method for determining the biochemical oxygen
demand (BOD) and dissolved oxygen (DO) in photographic processing effluents. New
York: The Institute.
Jouanneau, S., Recoules, L., Durand, M. J., Boukabache, A., Picot, V., Primault, Y., ... & Thouand, G.
(2014). Methods for assessing biochemical oxygen demand (BOD): A review. Water
research, 49, 62-82.
Mullis, M. (2013). A quick biochemical oxygen demand test (8th ed.). Washington, DC: U.S.
Government Printing Office.
Qiao, J., Hu, Z., & Li, W. (2016). Soft Measurement Modeling Based on Chaos Theory for
Biochemical Oxygen Demand (BOD). Water, 8(12), 581. doi: 10.3390/w8120581
Sinurat, M., Hasibuan, R., & Hasibuan, N. (2017). Pemanfaatan eceng gondok untuk menurunkan
kandungan biological oxygen demand (BOD), chemical oxygen demand (COD), pH, bau
dan warna limbah cair tahu. Jurnal Pendidikan Kimia, 9(3), 356-361. doi:
10.24114/jpkim.v9i3.8909